Composition means one class holds a reference to another, using the referenced class to help it fulfil its mission. Inheritance is the superclass/subclass relationship.
- The ++ operation concatenates two arrays
- The zip method picks corresponding elements in its two arguments and forms an array of pairs. For instance, this expression:
Array(1, 2, 3) zip Array("a", "b")
Will evaluate to:
Array((1, "a"), (2, "b"))